Current laundry detergent and fabric care compositions include a complex combination of active ingredients such as surfactants, enzymes (protease, amylase, mannanase, and/or cellulase), bleaching agents, a builder system, suds suppressors, soil-suspending agents, soil-release agents, optical brighteners, softening agents, dispersants, dye transfer inhibition compounds, abrasives, bactericides, and perfumes.
Mannanase enzymes, including endo-β-mannanases, have been employed in detergent cleaning compositions for the removal of gum stains by hydrolyzing mannans. A variety of mannans are found in nature. These include linear mannan, glucomannan, galactomannan, and glucogalactomannan. In each case, the polysaccharide contains a β-1,4-linked backbone of mannose residues that may be substituted up to 33% with glucose residues (Yeoman et al., Adv Appl Microbiol, Elsivier). In galactomannans or glucogalactomannnans, galactose residues are linked in alpha-1,6-linkages to the mannan backbone (Moreira and Filho, Appl Microbiol Biotechnol, 79:165, 2008). Therefore, hydrolysis of mannan to its component sugars requires endo-1,4-β-mannanases that hydrolyze the backbone linkages to generate short chain manno-oligosaccharides that are further degraded to monosaccharides by 1,4-β-mannosidases.
However, enzymes are often inhibited by surfactants and other components present in cleaning compositions, which interferes with their ability to remove stains. For instance, proteases in laundry detergents may degrade mannanases before the removal of a gum stain. In addition, mannanases may have a limited pH and/or temperature range at which they are active, which may make them unsuitable for certain formulations and washing conditions. Accordingly, the need exists for endo-β-mannanases that retain activity in the harsh environment of cleaning compositions.